This invention relates to a mechanical latch or fastener for joining the pieces of a plastic enclosure. For example, a plastic front panel or bezel can be secured to a plastic main panel or chassis using the latch of this invention. In particular, the pieces of this latch can be directly molded onto the panels and can be formed of the same materials as the panels.
Molded plastic enclosures are used to house electronic circuitry, such as computers, disk drives and video monitors. To reduce the cost of these enclosures, it is desirable that separate panels of the enclosure can be joined by simple latching or catch mechanisms, preferably molded directly into the plastic material. This eliminates additional separate screws, rivets, clamps or other fasteners. This invention provides a latching mechanism which can be molded directly into the enclosure material.
To improve the appearance of molded plastic enclosures, it is desirable that the outside surface of the assembled enclosure have a smooth, flush, finished appearance without screw heads or rivet heads, visible fasteners, or holes. This invention provides a "hidden" latch mechanism, which is not visible after the pieces of the enclosure are joined.
To be able to access the contents of a molded plastic enclosure, it is desirable that the enclosure can be easily disassembled and unlatched or opened for access to the internal components. This requires latches or fasteners that can be released or deactivated during disassembly, and then re-latched during a re-assembly process. This invention provides a releasable latch which can be easily unlatched for disassembly, and relatched for re-assembly.
Conventional molded plastic latch designs have several disadvantages. FIG. 1 shows a schematic cut-away side view of a conventional approach to a hidden, releasable, molded latch for joining two panels of an enclosure. First panel 10 has a projecting hook or projecting tang 12 molded on its inside surface near an edge. Second panel 20 has a hole 22 formed near a corresponding edge. When the enclosure is assembled by sliding panel 20 into panel 10, the projecting tang 12 can be captured in hole 22, thereby holding the panels from sliding back out of the assembled position. Of course, additional molded edges, guides and stops can be used to more precisely position and align the panels, but the basic restraining force holding the panels is provided by the capture of the tang 12 in hole 22. Note, that this conventional design requires that panel 20 be "within" or "nest inside" of panel 10 in order to properly operate and to hide the latch. Therefore, the seam between the panels will be a "step" or "offset" 32 rather titan a smooth, flush edge-on-edge abutment of the panels. To release this latch, an external force 30 is applied to panel 20 at a spot below the seam or offset 32. This force will deflect panel 20 inward, until the tang 12 is released from hole 22, and the panels can be slid apart.
FIG. 2 shows a schematic cut-away side view of a conventional approach to a flush-surface, hidden, releasable, molded latch for joining two panels of an enclosure. FIG. 2 is similar to FIG. 1, with similar parts numbered correspondingly. Again, first panel 10 has a projecting tang 12 molded onto its inside surface. Second panel 20 has an edge formed with a projecting latch tab 24. Tab 24 extends inside and parallel to first panel 10. Tab 24 has a hole 22 molded in it. The edge of panel 20 provides a recess into which the edge of panel 10 will rest, in order to provide a "flush" seam, rather than a seam with an offset 32 of FIG. 1. When the enclosure is formed by sliding panel 20 against panel 10, tab 24 slides within panel 10, and the projecting tang 12 can be captured in hole 22, thereby holding the panels together. Note, that this design requires that the tab 24 which has hole 22 is contained "within" or "inside" of panel 10 in order to operate and to hide the latch. However, the seam between the panels will be flush rather than offset. In order to release this latch, a means to deflect tab 24 away from tang 12 must be provided. Conventionally, this is done by providing a hole 34 in the first panel 10 at a location opposite the end of tab 24. If a tool 36 is placed in the hole 34, then an external force 30 can be applied to tab 24 to deflect it and release tang 12 from hole 22. Overall, in this conventional design of FIG. 2, the desired flush surface has been achieved at the trade-off of a hole 34 for use in releasing the latch.
From these examples of conventional approaches it can be seen that what is desired is a hidden, releasable, molded latch which allows flush surfaces and no external holes.